Combination fuze



Oct. 21, 1958 c. F. BOWERSETT- EII'AL 2,856,354

v COMBINATION FUZEI Filed Oct. 17, 1945 S SheetsShe et 1 3 wu urn bow a Z'Bowenseii JM mezer c. F. BOWERSETT ETAL Oct. 21,1958

I COMBINATION FUZE 3 Sheets-Sheet;

I Filed Oct. 17, 1945 I LfFBowens JMvWwezer W M v 2 f: m. .M

' inertia generator device therein for commnrrownuzn Charles F. Bowersett, Arlingtomfla and I John M. Wheeler, Greeley,-Colo'.

Application October '17; 1945, Serial 110,622,921

7 Claims. (Cl. :102 ,7 1). x

(Granted'lmderTi'tle 35, Us SL 'Code (1'952)sec.'266)" This invention relates to-a-combinat-ionfuze for a bomb for destroying enemyordnance storagei depots,

and thelike and is adapted to be dropped fr'om'an aircraft in flight and fire upon'impact withthe target'or by an electrical impulse; When'the'iuze is fired electrically,

'either on striking the target or-=in the vicinity thereoflas the case may be, it will be understood-that the bomb is preferably 'mountedon a robot plane or glider plane and means areempl'oyed'wherebythe bombis' exploded electrically on impact with the target-or electrically by remote control apparatuswithin'the'plane as is well known in v The device of v i the present'invention may also be used for destroying airthe art to which the invention pertains;

craft, secret'equiprenrand the like employed thereon by demolition; 'in'the event that the aircraft has beendisabled due to enemy gun fire and thecraft'is likelyto fall into enemy hands. Under such conditions it has been found necessary'to destroy the plane and equipment by :demoli- 'tion'and for thispurpose it is necessary to provide a fuze which can be armed and fired after a predetermined period of time vhaselapsed'sufficient to allow time for the crew members of the plane toLbail'out before the demolition charge is fired;

One of the objects'of"theinvention is the provision .of a'newand improvedfuze for a'bomb adapted to be detachably secured to'a' bombcasing and having arming means arranged therein adapted to be released and actuated .tozan armedtposition during th'e'free flight of the bomb toward the target,and firing means therefor including an electroresponsive detonator "and impact firing means for firing the explosive charge disposed within the bomb.

Another obje'ctofthe invention'is the provision of a new and improved fuze for a b'omb'having "slideable armingjmeans releasably'arranged therein'in an initial safe positionand including means forreleasing the slideable arming rncansdtiring the free flight of the bombtoward the target. I

Another object of the invention.is"the provision of a new'and improved'fuze for a bomb havinga slideable arming member arranged therein in which the arming member is. maintained in an initial safe position .and thereafter locked in an. armed position.

Another. object of the invention is the provision of a -fuze having a slideable armingmember arranged therein and means rotatably' supported onthefuzeand adapted to release the arming member when rotated a predetermined amount whereby thefuze is .armed,'the .fuzealso being provided with dual .means for firing the explosive charge within the fuze a'fterthe fuze has been armed and uponimpactof the bomb with the target Another object tof the invention isthe provision of a new and improved fuze for abomb, jthe fuzed bomb being adapted to .be 'arrangedin'a glider plane having generating a voltage suflicient to-fire-the bomb upon impact of the bomb with the target orfired at-=will by atradio signal'on or within the vicinity ofwthe target.

' United States Patent 1 "ice iatentedOct. 2.1, 1958 A further object of the invention is the provision'of 'a new and improved -fuze for .a 'bom'b having normally locked rotatable arming'means and a slideablearrning member maintained in an initial safe position by'the arming means. and adapted to moveto an armed position after the rotatable arming means has beenreleased'and rotated at predetermined amount.

Still further objects, HOVClfCQfUI'CS and advantageswof the invention will become. apparent fromithe following description taken in connection with'the accompanying drawings, wherein:

Fig. 1 is an elevational' view partly'broken away ofa fuze constructed in accordance with the present "invention andshowing a fragmentary portiont'of-a'bomb and "the manner in which the fuzeyis' attached thereto;

- Fig.2 is a central longitudinal sectionalview taken'substantially on line 22 of Fig. '1;

Fig. 3 is a front elevational' view ofFig. 1;

Fig. 4 is aview similar to Fig. 2 bnt'showing the fuze in an armed position and the conductor plug thereof'replaced by a cap;

Fig. 5 is a fragmentarysectional view takengon'line 5 -5 of Fig.4;

Fig. 6 is an enlarged sectional view-taken on'line 6 6 of Fig.4;

Fig; 7 is anenlarged sectional .view'takenon line 7-+-7 of Fig. 4;

Fig.,8 is an enlarged 'fragmentarysectional view .ofa portion of the fuze showing the arming member locked in an.armed position;

Fig.9 "is an enlargedsectional-view taken-on line 9.-9

present invention is attached thereto; h

Fig. 10.,is an elevationalview-of a combination mine 'and bomb showing the manner in whichthe device of the Fig. 11 shows in diagrammatic form a circuit arrangement suitable for operating the fuze from a current generator; and p Fig. 12 shows in diagrammatic form-a cirjcuitiarrangement for operating the fuze by a radio signal.

Referring to the drawings in-detail for a more complete understanding of the invention, the tuze 10 disclosed thereoncomprises a casing or housing 11"composed of any material suitable for the purpose'such, for example,

as steel, brass-or the like;

As shown on the drawings,"especially Figs; 1," Zand 4 thereof, the housing'll of the fuze 10 is 'deta'chably secured to a bombcasing 12 by an adapter generally indicated by the reference character '13 comprising an an- "nular member "14 having a threaded nippleli-iritegrally formed thereon and adapted to have threaded'engagementwith a threaded opening 16 provided in the casing 12 of the bomb.v A'plurality of recesses 17 are provided in the annular member 14 whereby a spanner wrench-orthe like may be employed for screwing the adapter 13 intothe threaded opening 16 provided in the casing'12" ofthe bomb.

The housing 11 is provided with an enlarged head 18 having a reduced screw threaded portion 19 formed thereon'adapted to engage an internally threaded portion 21Iprovided on the adapter-13 whereby the fuze 10 is detachably securedito the adapter. Theh'ousing 11'is also provided with a cylindrical member 24 integrally 'formed'on the portion 19. thereof and extending apredetermined .distance into a tube 25, thetube being secured to the .adapterlfl in any. suitable manner, thereby providing a .chamber for enclosing the housing .11,-and also isolating a demolition charge 26 therefrom. Secured to. the lower portionof the cylindrical member 24 of. the housing-11 is atubular member27thaving one end there- Of'ZClOSEd' asoat 28 thereby to receive-and,- support. :an exbore 49 extending through a nipple 51.

plosive booster charge 29 arranged within an annular container 31, the container being in registered engage- .member 27 is secured to the cylindrical member 24 in any suitable manner but preferably by threading the member 27 into a threaded portion 32 provided on the lower end portion of the cylindrical member 24. Y

A plunger or arming member 33 is slideably arranged within a cutout portion 34 also provided in the lower end portion of the member 24, and the blocl is arranged in abutting'relation with respect to the lower end portion of the member 24 being secured thereto by screws 36 thereby slideably maintaining the arming member within the cutout. portion 34. The arming member 33 is urged toward an armed position by a pair of springs 37 enclosed in tubes 38, one end of each tube being closed as at 39.

The other end of each tube 38 is respectively secured within a recess 41 provided in the plunger 33 thereby providing means for moving the plunger to an, armed position after the plunger has been released, as will be hereafter more fully described. The arming member 33 is releasably locked in an initial safe position as shown on Fig. 2 of the drawings by a moveable firing pin 42 having one end thereof extending a predetermined distance into a recess 43 arranged within the arming member. The arming member 33 is also provided with a bore 44 having a sensitive primer 45 disposed therein which is adapted to be moved into alinement with a leadin charge 46 arranged with an opening 47 provided in the block 30 thereby to establish an operative explosive train between the primer 45 and the booster charge 29 when the arming member is in armed position.

As shown on Figs. 2 and 4 of the drawings, the firing pin 42 is rigidly supported within a sleeve 48, the sleeve having. threaded engagement at 50 with a portion of a The nipple is secured within the housing ii in any suitable manner preferably by being threaded into an opening 52 provided in the housing ll. The sleeve 43 is provided with a reduced portion 53 formed thereon and extends through an opening 54 arranged in an annular member 55 provided in the member '1 and disposed Within the bore 49. The sleeve 48 is adapted to engage the annular member 55 thereby preventing further movement of the firing pin into the recess 43 provided in the arming member, and thus the arming member is maintained in initial safe position by the firing pin until the firing pin has been withdrawn from the recess 43.

Secured on one end of the sleeve 48 is a propeller 56 having a conical hub 57 and aplurality of blades 53 extending therefrom adapted to rotate the sleeve during the free fiight of the bomb toward a target. The propeller 56 is secured to the sleeve in any suitable manner but preferably by a dowel pin 59 forced into an aperture in the end of the sleeve and extending into an opening 61 provided in the hub 57 thereby locking the propeller to the sleeve for rotative movement therewith. The propeller 56 is maintained in locked position on the sleeve 48 by a bolt 68. By this arrangement it will be understood, however, that rotative movement is imparted to the sleeve 48 by the propeller as the result of the pressure of the air against the propeller blades 58during the free flight of the bomb toward a target. As the sleeve rotates within the threaded portion of the bore 49 outward movement is also imparted thereto due to a complementary threaded portion on the sleeve engaging the threaded portion of the bore 49 and also due to the rotation imparted thereto by the propeller as heretofore described. Thus the firing pin secured to the sleeve is withdrawn from the recess 43 provided in the arming member and the arming member is released and is urged under tension or" the springs 37 to the armed position as shown on Figs. 4, 6, 7, and 8 of the drawing. It will be understood, however, that the propeller is adapted tomake a predetermined number of revolutions before the firing pin is withdrawn fromthe arming member, after which a stop 62 secured on the other end of the sleeve 48 engages the annular member thereby preventing further movement of the sleeve and thus the striker 63 of the firing pin 42 is maintained in predetermined spaced relation with respect to the sensitive primer 45 and upon impact of the bomb with the. target the striker 63 fires the primer 45.

The firing pin 42 is adapted to move freely through a hove 64 provided in the portion 24 of the housing 17 and When the arming member 33 is in an armed position the sensitive primer, lead-in charge and booster charge are in line with the firing pin and upon impact of the bomb with a target, the threads 50 are sheared and the striker 63 is driven through the bore 64 and into the sensitive primer with sufiicient force to fire the primer thereby to initiate firing of the demolition bomb.

It will be understood, however, that selective operation of the fuze may be obtained by arranging the sleeve member 48 in such a manner as. to permit the threads 50 to shear and the fuze to function on impact with targets comprising different degrees of resistances, and also so constructed as to function at one velocity and not function at another velocity. For example, the fuze may be so constructed as not to function on water upon impact therewith when the bomb is dropped from a distance of 5,000 feet, but will function on light armor plate when dropped from a distance of 50 feet. If desired, the fuze may be so constructed as not to function upon impact with a body of water when the bomb is dropped thereon at an altitude of 5,900 feet, but will function upon impact with a body of water whendroppedfrorn an altitude greater than 5,000 feet. x

As shown on Fig. 7 of the drawings the arming member 33 is locked in the armed position by a pair of detents 65, each detent being provided with a reduced portion 66 adapted to extend into a pair of openings re spectively arranged inthe portion 24 of the housing 11 after the arming member has been released and has moved to an armed position. The detents are slideably arranged within a pair of bores 67 provided in the arming member 33 and adapted to be urged outwardly by'a spring 68 disposed within the bore and having each. end thereof respectively engaging a detent thereby locking the arming member in an armed position. To assure locking of the arming member in an armed position, as shown on Fig. 8 of the drawing, a spring pressed detent 69 is employed. The detent69 is arranged in a bore 71 provided in the block 3% and is normally maintained within the bore by abutting engagement with the arming member When the arming member is in the initial safe position. It will be understood, however, that when the arming member has been released and moves to an armed position the detent 69 is adapted to be urged itno a recess '72 arranged in the arming member by a spring 73 thereby providing additional means for locking the arming member in an armed position. i

As shown on Fig. l of the drawings means are provided Wherebyrotation of the propeller 56 is prevented and arming of the fuze will not occur until the propeller has been released. The releasing means including an annular member 74 surrounding the portion 19 of the housing 11 and held in clamping engagement with the member-14 of the adapter 13 by the enlargedhead 18 of the housing. The annular member 74 has a bifurcated retaining member 75 formed thereon for detachably supporting a releasing device 76, the releasing device including a rod 77 resting in the bifurcated portion and having one end thereof extending between a pair of the propeller blades 58 and the other end having a supporting pin 78 secured thereto in any suitable manner whereby the releasing device 76 is supported in operative relation with respect, to the propeller. The pin 78 supporting the rod 77 is releasably maintained in a pair of registering apertures 79 disposedinthe.retaining member 75' by a frang-ible. wire 81-.composedofiany. material suitable for :thepurpose such, for example as'lead, the wire being adapted toizpass throughan eyef'821-formed on ,the upper end of the pin 78 and -also adapted,to pass about the bifurcated'portion of the retaining member 75, the free end thereof being secured together as at 83 thus maintaining the-rod 77in locking relation withrespect to the .propeller 56.

. One end; of a safety wire84 is secured to the eye 82 of the pin 78:.as shown in-Figs. 1, and 3 for forcibly removingthe releasing device 76 from the retaining member thereby to .arm the fuze, the other end of the safety wire -8 4-being adaptedto extend into theaircraft or robot plane, as thecase may be .(not shown), and be actuated in-.any suitable.=manner.such, for example, as by a me- .--chanical device or,'if desired, it may be manually operated. 1min be understood, however, as the bomb is released from' an aircraft in flight and falls away there- @tfrom the satetywirec84 isadapted to pull the release "device 77 away from the retaining member 75 thereby releasing the propeller 56 and permitting free rotative movement-of the propeller during the free flight of the -bornb toward.the target. As the propeller rotates the sleeve sectireddhereto. also rotates in such a manner as to. move the firing pin 42-mounted in the sleeve out of -the-recess 43 of the. arming member 33. -When this -occurs-the :arming member 33 is urged into an armed ,position, Fig. 4, in response .to the pressure exerted thereon by the springs 68, the arming member being main- ---tained--,in the armed :position as heretofore described. It will also be understood,'however, that the firing pin 42 is moved aprcdetermined distance away from the armingrmember. during the downward. flight of the bomb tovward the target and upon impact of the bomb with the --target the striker.63'of the firing pin 42 is driven into the primer 45 with sufficient force to cause firing thereof thusinitiating. firing ofthe-lead-in charge .46, the booster charge-29, and the demolition charge 26.

;While the foregoing description pertains to a fuzefor a bomb which is adapted to be dropped from an aircraft in .flight'upona target and to-be mechanically detonated upon impact therewith, it willbe understood that the fuze is also providedwith an electroresponsive detonator 85 wherebythe-bomb may be exploded at will by remote control in response .to, an electrical impulse supplied thereto from any suitable sourcesuch, for example, as a radio receiving set arranged within the aircraft upon which the bomb .is mounted, Fig. 12, or by an inertia operated current generator also mounted therein which is adaptedtosupply sufficientourrent through the electroresponsive detonator 85 to explode the bomb upon impact ofthe aircraft with the target, Fig. 11. The electroresponsive detonator 85 is arranged within a recess 86 -providedin the portion 24 of the-housing 11 and maintained therein by a screw threaded plug 87 having abutting -relation with respect to one end of the detonator 85 and also having threaded engagement with a portion of the recess 86 The enlarged head 18-of the housing 11 is provided with a screw threaded opening 88 having threaded therein an electrical socket 89. The socket has secured thereto a pair ofv electrical conductors 91, the conductors being disposed in a:groove'92 provided in the housing 11 and also passing through an opening 93 provided in the plug 87. The otherend of each conductor 91 is connected to the electroresponsive detonator 85 arranged within the I recess 86 thereby providing a firing connection from the --'socket 89-.to the detonator 85.

As best shown in Figs. 1,2 and 3 01? the drawings, a conductor plug 94 is connected to the socket member 89 ---in any suitable manner, the. plug having one end of a epair; of electrical ,conductors' 90 secured thereto, the other I ends of conductors being connected to a source of electrical power and to a' time delay device (not shown),

such time delay device being in electricalconnection with a battery' or the like forsupplyingfelectricalcurrent to the detonator'SS' as the circuit is closed'by the time delay device.

Incommunication with the recesses -44 and 64 inthe housing 11 is a flash chamber 97 providing means whereby a flash from the detonator,85,.when fired, is adapted to 1 pass therethrough'and' fire the primer 45 thereby to cause the, bomb to explode as is well'known todhosefskilled in the art. 7

It will also be'un'derstood, howeverythat any electrically or mechanically operated time delay device'suitable for the purposemay be employed in the firing circuit whereby a predetermined period of time will "elapse after the timedelay device has been set inoperation before the detonator will be fired, therebylallowing sufiicient time to elapse for the personnel of 'the disabled 'planeon which the bomb is mounted to bail outbe'fore the' bomb 'explodes. The force of'the'ex ploding bomb-will*be-'-sufficient to demolish'completelythe plane and the secret equipment therein, 'thus preventing the'plane "and the secret equipmentf from'falling into enemyhandsintact.

Aprotector cap '98 is secured to a threaded portion of the socket member'89 thereby" enclosing the'electrical contactmemberofthejsocket therein, thus preventing damage thereto and alsopreventingmoisture and foreign in a robot orQgliderplanefthe cap 98 is removed and the, conductor pl1. 1g"9 4"is connected to-the socket'89 in lieu thereof when'the 'plane'iri which the bomb is mounted is about to be launched or'a'bout to -take otf thereby providing a firing connection by 'way of the cable -96 from the source of electrical power'included in'thefiring circuit and operatively connected toa radio receiving set, inertia operated current, generator or a time-delay device as the case may be.

During transportation and "handling of I the'- 'bo'mb, rotative movement of the propeller'56, isprevente'd by a seal shown indashed outline on Fig. 2 of the'drawings and including awire 99"whichextends through an opening 101 in the housing lland; also extendsthrough an opening 102 in the propeller, the free end of the wire 99 being sealed -within a lead disk' 103. Thus the-Propeller is prevented from rotating-andthe arming m'ember is maintained in safe position by the firing pin 42 as shown in Fig. 2 of the drawingsuntil the-*seal has been broken and the wire removed.

On Fig. 11 is shown in diagrammatic form a circuit arrangement suitable for-operating the fuze-from an inertia operated current'generator" lM such, for example, as the current generator disclosed and claimed in the copending application-of Harold JQPlumley-forMagnetic Inertia Controlled Fuze, Serial No. 535,799 filed *May 16, 1944. It will-beunderstood, -however,'thatwhen the fuze is adapted 'to be fired 'by theinertia generator-104, a glider or the like may be employed, such glider having arranged therein in any suitable-manner'the fuzedbomb and inertia generator. -Theglider 'is adapted to -be released in any suitable manner from-a carrier'plane'or the like toward the target and upon impact'therewith the inertia generator is adapted to generate" a voltagesufficient to fire the low energy detonator device as is well known to'those skilled in-the art. -It-willbe further, understood that the propeller 56 is adapted to be released for rotative-movement'as the glider is released from the carrier plane thereby allowing free rotation of 'the propeller so that arming of the fuze is accomplished lar ordnance devices.

:signal, a robot :plane: or the like is employed having ar-. I iranged therein the fuzed bomb: and a radio receiving set- 105 thereby permitting therobot plane to be guided to- 1 :ward; the; target. by. a fradio signal and, also: providing I means wherebythe bomb may be 'fired at will :on, or I within thevicinity: of the target E up by the receivingset 105; I I I I I Whereas, the invention has been described. in :detail I with respect to a bomb for demolition purposes; it isobviouslynot so. limited as it may also. be employed; for firing rockets,- glider. bombs,; incendiarybombs and sim'i- The many advantages ofthe fuze' I constructedin accordance with the present invention will.

I bereadily apparentfrom the foregoing description, taken a I I I in connection with vthe accompanyingv drawings and, 'al-:

' though a preferred embodiment of the device'is' illustrated I I and described, it: is to .be understood that changes; in the- I I I details. of construction and in the combination and a'r-i I i range'ment ofip'arts may be resorted'to which fall w'ithi I the scope of the invention as' claimed, I

II The invention herein-described and claimed'may; be i manufactured and used by or for the Government-ofthe- I United States. of- America for governmental purposes I v I without the-payment. of any royalties thereon or therefor. I 1 What. is claimed as new andde'siredto be secured. by: 3 Letters Patent of; the United States is: l .I I I I I I I 1. A combinationfuze for 'a. bomb adapted to be selectively .fired by impact with a target or by electricai I impulse receiving means, said am comprising a casing. I I supported; by the bomb and extending a predetermined. distance therein, an explosive charge arrangedwithin said i I casing, a releasable arming member slideably supported within said casing. and having an explosive element posis I I tio'ned thereby in an initial safe position, means including I I a firing pin rotatably fsupported within: said casing for releasably maintaining the arming member in said initial I I safe position and: adapted to-release said arming mem- I her to. position said elementin firing reiationwithrespect I I I l to said-firing'pinand said electricalimpulse firing means when the I rotatable means: has rotated a predetermined amount, means including a frangible threaded portion on said rotatable means for imparting outward movement thereto as the rotatable means rotates and constructed and arranged to be sheared as the firing pin moves to engage said element forcibly in response to said impact, means arranged within said arming member for urging said arming member from said initial safe position to said armed position when said arming member has been released, means for locking said arming member in the armed position whereby said rotatable means is adapted to fire said explosive charge as said frangible threaded portion is sheared in response to said impact should said electrical impulse means fail to receive an electrical impulse.

2. A combination fuze for a bomb adapted to be selectively fired by impact with a target or by an electrical impulse receiving means and comprising a casing supported by said bomb, a booster charge arranged within said casing, 21 releasable arming member slideably supported within said casing in an initial safe position, a sleeve rotatably supported within said casing, a firing pin secured within said sleeve for releasably maintaining said arming member in said initial safe position and adapted to release said arming member and arm said impulse firing means when said sleeve has been moved outwardly in response to a predetermined number of revolutions thereof during the free flight of the bomb from the aircraft toward said target, a propeller secured to said sleeve and adapted to impart rotative movement thereto, a plurality of frangible threads on said sleeve for causing said sleeve to be moved outwardly as the sleeve is rotated and constructed and arranged to be sheared as the sleeve moves inwardly in response to said impact, a pair of springs arranged within said arming member for urging said arming member .to an armed position when said I arming member has been re'lea'sed by'said firing pin,:and I I means for locking: said arming member in said armed- I position whereby the firing 'pin is adapted to fire: said I I by a radio signal {picked I I I within. said-casing in'arr initial safe ,posi-tion,'a'sleeve ro mca ns fail to receive an impulse; I

: .3. A fuze for a bomb adapted to be dropped on a i I target from an aircraft. in fiight and comprising a casing. 'supportedby the bomb and extending a predetermined distance therein, .a booster charge arranged within said I booster charge as said frangible threads? are sheared. in

I response to said impact should said electrical impulse I ":Sing', a reieasable. arming: member slideably supported vtata bly supported within said casing, a firingzpinisec'ured within said'sleeve for releasably maintaining said arming :1'5

: lcasethe arming member when the sleeve has :been ro tatedapredetermined. number of. revolutions, means for rotating the sleeveduring t'he fre'efiig'ht of the bomb. from I the aircraft toward said target, means includinga frangible t threaded portion. on .said sleeveforqirnpartingoutward i move'ment the'reto as the sleeve is rotated and'constructedz and arranged tobe sheared as the sl eeve moves .inwardiy' f I inresponsetoimpact of said bomb with a target-, means 'arranged within saidarming member for urging'said arm-. 3 I 3 ving member to an armed position when said: arming mem-i berjhas beenireleasedby said firing pin, andmeans for locking said I arming member :in said armed position I whereby said tiring pin: is adaptedto fire :said booster I I charge as said frangible threaded portion issheared and.

the sleeve moved inwardly upon: impact ofs'aid bomb with 3 member in said initial safe position. and adapted: toresaid target. I

I I I 4; A'fuze' for a bomb adapted tobedropp'ed on a target I from an aircraft in flight and. comprising an adapter, acomplcmentaryv member supported I by :said adapter, '2

I container.supported by said complementary member, .a.

booster {charge arranged: within said I container, a fre .leasable arming member slideably. supportedwithinsaid;

cornpiementary member in an. initial safe. position, a

sleeve rotatably; supported within. said complementarymember, a firing pin secured within. Said sleeve: fOT'I'E-e' II I lea-sably maintaining said arming member in said initial safe position and adapted to release the arming member when said sleeve has been moved outwardly a predetermined amount, a plurality of frangible threads on said sleeve for causing the sleeveto be moved outwardly as the sleeve is rotated and constructed and arranged to be sheared as the sleeve moves inwardly in response to impact of the bomb with said target, a propeller secured to said sleeve and adapted to impart rotative movement thereto during the free flight of the bomb toward said target, a pair of springs arranged within said arming member for urging said arming member to said armed position when said arming member has been released by said firing pin, and a pair of spring actuated detents arranged within said arming member for locking the armiug member in said armed position whereby said firing pin is adapted to fire said booster charge as said frangible threads are sheared and the sleeve moves inwardly upon impact of said bomb with the target.

5. A fuze for a bomb adapted to be dropped on a target from an aircraft in flight and comprising a casing supported by the bomb, a boostercharge arranged with in said casing, a lead-in charge also arranged within the casing in operative relation with respect to said booster charge, a releasable arming member slideably supported within said casing in an initial safe position, a sleeve rotatably supported within the casing, a firing pin secured within said sleeve for releasably maintaining said arming member in said initial sate position and adapted to release the arming member when the sleeve has been moved outwardly a predetermined amount, means including a plurality of frangible threads on said sleeve for causing the sleeve to be moved outwardly said predetermined amount as the sleeve is rotated and constructed and arranged to be sheared as the sleeve moves inwardly in response to impact of the bomb with said target, means secured to said sleeve for preventing further rotation of the sleeve when the sleeve has been moved said pair of resilient members arranged within said arming member for urging the arming member to an armed position after the arming member has been released by said firing pin, means for locking said arming member in said armed position, and a sensitive primer arranged within the arming member and adapted to be moved into registered relation Withsaid lead-in charge when the on a target from an aircraft in flight and comprising a casing supported by the bomb, a booster charge arranged within said casing, a releasable arming member slideably supported within said casing in an initial safe position and being movable to an armed position when released, a sleeve rotatably supported within the casing, means secured to said sleeve for imparting rotative movement thereto, frangible threaded means on said sleeve for coacting with complementary means on the casing for causing outward movement of the sleeve as the sleeve is rotated, a primer carried by said arming member and arranged to be moved into firing relation with said charge when the arming member is in said armed position, and a firing pin secured to and movable with said sleeve for releasably maintaining said arming member in said initial safe position and for releasing the arming memher when the sleeve has been moved outwardly a predetermined amount, said firing pin being driven into firing engagement with the primer as said frangible threaded means is sheared upon inward movement of the sleeve in response to impact of the bomb with said target thereby to fire said charge and explode the bomb.

7. A combination fuze for an aircraft dropped bomb comprising, in combination, a casing supported by the bomb, an explosive charge arranged within said casing, a primer, a releasable arming member for moving said primer from a safe position into operative firing relation with respect to said charge when the member is released, means including a firing pin arranged initially in locking engagement with said arming member for retaining the arming member in safe position until the pin is withdrawn therefrom, means forming a frangible threaded connection between the casing and said retaining means for withdrawing the firing pin when the retaining means is rotated a predetermined number of revolutions, means including a propeller operatively connected to said retaining means for causing said predetermined rotation thereof during the free flight of the bomb through the air, an electroresponsive detonator for firing said primer, means forming a passageway for connecting said detonator in firing relation with respect to said primer when said firing pin is withdrawn, and means including an inertia operated current generator for supplying an electrical firing impulse to said detonator as the bomb strikes the target, said threaded connection being sheared for enabling said firing pin to be driven into firing engagement with the primer in response to said impact, thereby to explode the bomb when said generator fails to fire the detonator.

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